The Immunostimulatory Effect of Probiotic Conditioned Medium on RAW264.7 Murine Macrophages

Abstract Probiotics are a mixture of beneficial live bacteria and/or yeasts that naturally survive in our bodies. Recently, loads of studies have focused on their role in the immune system and digestive tract. This study examines the immunostimulatory effect of commercially available-probiotic conditioned medium (CM) on RAW264.7 murine macrophages. Probiotic CM has been prepared by culturing the commercially available probiotic in a cell-culture medium overnight at 37°C, followed by centrifugation and filter-sterilization to be tested on macrophages. The immunostimulatory effect of different dilution percentages (50%, 75%, 100%) of CM was examined using MTT assay, pro-inflammatory cytokine (tumor necrosis factor TNF-alpha) production in macrophages., migration, and Phagocytosis assays. For all the examined CM ratios, the percentages of cell viability were > 80%. Regarding the migration scratch, TNF-alpha and phagocytosis assays, CM demonstrated a concentration-dependent immunostimulatory effect. However, the undiluted CM (100%) illustrated a significant (p-value < 0.05) stimulatory effect compared to the positive and negative control. The findings suggest that the secretions and products of probiotics, as measured in CM, may be closely linked to their immune-boosting effects. Understanding this relationship between probiotic secretions and immune function is crucial for further exploring the potential benefits of probiotics in enhancing overall health and well-being.